The Prime Minister, Margaret Thatcher, has failed to win outright victory in her battle against former Defence Minister Michael Heseltine for the leadership of the Conservative Party.

The vote results, announced at 1830 GMT, gave Mrs Thatcher 204 of the 372 votes against 152 for Mr Heseltine, leaving the prime minister four votes short of the 56 majority required. Sixteen MPs abstained.

The contest now goes to a second round, seriously undermining the prime minister's authority within her own party.

Pandemonium

There was pandemonium among Conservative MPs huddled outside the committee room in Westminster to hear the news.

Thatcher supporters reacted with anger that the contest would be prolonged by another week, and strongly criticised the leadership system which allowed the challenge in the first place.

Mr Heseltine's supporters were confident he could pick up enough votes on the second ballot to win.

The leadership contest was triggered by the devastating resignation speech last week of the Deputy Prime Minister, Sir Geoffrey Howe, in which he was highly critical of Mrs Thatcher's methods.

Fighting on

Mrs Thatcher will now face intense pressure to stand down when she returns tomorrow from the European security summit in Paris.

However, within minutes of hearing the result, she addressed reporters and photographers on the steps of the British Embassy to say it was her intention to fight on.

"I am naturally very pleased that I got more than half the parliamentary party and disappointed that it's not quite enough to win on the first ballot. So I confirm that it is my intention to let my name go forward for the second ballot," she said.

Mr Heseltine expressed gratitude for a formidable vote and said he too would press on, ignoring rightwing appeals to him to stand down.

Election call

The Labour opposition leader, Neil Kinnock, has tabled a motion of no confidence in the government and called for an immediate general election.